This invention relates to an apparatus for processing and working continuous webs or discrete sheets of materials, including, for example, plastic films, non-woven substrates, metal foils, paper, absorbent pads, and the like. More particularly, the invention relates to a force-adjustable rotary apparatus for cutting, embossing, bonding, printing, etc., such webs or sheets of materials.
Rotary web or sheet converting devices and setups are known, especially, for use in high speed applications for cutting, embossing, bonding and other process operations for working continuous webs or discrete sheets of materials. Such devices and setups usually involve the use of oppositely rotating rolls, one of which may carry one or more processing tools, and another roll which may serve as an anvil against which the material is worked by the processing tool. As the rolls rotate, when the tool and the anvil meet to work the web or sheet of material, the force applied between the tool and the anvil is an important factor affecting quality and efficiency of the operation. This is because the force affects the wear of the tool and, therefore, the frequency of downtime of apparatus for changing or repositioning the tool. The amount of force that the tool exerts on the web or sheet depends upon the engagement of the tool against the anvil surface. Very small differences in the engagement may result in substantial changes in the amount of the force, and this, in turn, may affect the longevity of the tool. The accuracy of the engagement may become even more important for relatively large tools when even a very small misalignment of the tool in relation to the anvil may subject a part of the tool to excessive forces, which in turn may result in accelerated wear of that part of the tool. Thus, because the amount of force between the tool and the anvil in a conventional rotary apparatus depends upon engagement of the tool against the anvil, a conventional rotary apparatus requires precise positioning of the tool in relation to the anvil.
Further, due to the required accuracy of the positioning of the tool, a conventional rotary apparatus generally involves substantial setup time to manually position the tool relative to the anvil. The manual setup may require a complete shutdown of the machine which, in turn, results in significant downtime and inefficiency.
Still further, during working of the material, as the tool gradually wears and deteriorates, the quality of the working may also deteriorate. Usually, the quality can be recaptured by increasing the force between the tool and the anvil. For conventional rotary apparatus, this means changing the engagement of the tool in relation to the anvil by repositioning the tool radially toward the anvil. Because a conventional rotary apparatus does not have the capability of changing the force during rotation, the change in force may require that the machine be shutdown, thus resulting in significant downtime. Therefore, in order to extend the time between shutdowns, the tool is usually adjusted to provide a larger than immediately needed increment of engagement. However, the drawback of this procedure is the generally reduced overall tool longevity due to more accelerated wear of the tool as the larger increments of engagement result in higher forces between the tool and the anvil.
Yet another drawback of a conventional rotary apparatus is that the apparatus generally requires different engagement between the tool and the anvil at lower rotational speeds than at higher rotational speeds, i.e., less clearance or more compression or interference between the tool and the anvil at lower rotational speeds than at higher rotational speeds. Because conventional rotary apparatus does not have the capability of changing the engagement of the tool during rotation of the tool, the tools are usually set for engagements suitable for lower rotational speeds to ensure satisfactory working of the material during machine startup. Working at higher rotational speeds (i.e., at production speeds after machine startup) with engagements suitable for lower rotational speeds may result in excessive forces between the tool and the anvil during higher rotational speeds. The effect may be accelerated wear of the tool at production speeds.
Thus, a conventional rotary apparatus exhibits a number of drawbacks which lead to operational deficiencies due to the initial setup time required, the frequency and duration of downtime necessary to maintain the proper operation, and the reduced longevity of the tool.
Accordingly, it may be desirable to provide a rotary apparatus which overcomes certain of the drawbacks exhibited by conventional rotary apparatus. Specifically, it may be desirable to provide a rotary apparatus which permits precise adjustment of the force between the tool and the anvil with minimal or no downtime. Further, it may be desirable to provide a rotary apparatus which employs a fluid pressure means for ready and quick adjustment of the force between the tool and the anvil with minimal or no downtime. Even further, it may be desirable to provide a rotary apparatus which enables one to reduce the time needed for changing the tool.
In order to overcome the drawbacks of current rotary apparatuses, the present invention provides a rotary apparatus suitable for processing and working a web or sheet of material such as plastic films, non-woven substrates, metal foils, paper, diaper cores and the like. Such an apparatus preferably includes a) a frame; b) an anvil roll (or similar component carrying an anvil surface) which is rotatably mounted on the frame; c) a tool roll (or similar component capable of carrying a tool) which is also rotatably mounted on the frame opposite the anvil roll; and d) drive means for rotating the anvil roll and the tool roll in opposite directions in a manner suitable for feeding the web or sheet of material being worked between the anvil roll and the tool roll. The tool roll has at least one processing tool associated with it. Such a tool is suitable for working the web or sheet of material which is positioned between the anvil roll and the tool roll. The apparatus also includes at least one chamber which includes a fluid and which is in force-transmitting communication with either the processing tool or with the anvil surface of the anvil roll or both such that a change in the fluid pressure (hydraulic or pneumatic) within the chamber serves to alter the force that is applied by the processing tool to the web or sheet of material being worked. Preferably the apparatus also includes means for changing and adjusting the pressure of the fluid within the chamber.